<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="./css/reset.css">
    <style>
        .menu{
            width: 150px;
            height: 300px;
            border: 1px solid #000;
            position: relative;
            /* 给我们看 */
            left: 100px;
            top: 100px;
            /* box-sizing: border-box; */
            z-index: 9999;
        }
        .menu li{
            height: 30px;
            line-height: 30px;
            text-align: center;
            border: 1px solid #000;
        }
        
        .menu .right_list{
            width: 400px;
            height: 500px;
            background-color: orange;
            position: absolute;
            left: 150px;
            top: -1px;
            box-sizing: border-box;
            border: 1px solid #000;
            display: none;
        }
        .menu li:hover .right_list{
            display: block
        }
    </style>
</head>
<body>
    <div class="menu">
        <ul>
            <li>
               <span> 1111</span>
                <div class="right_list">
                    AAAAA
                </div>

            </li>
            <li>
                <span>2222</span>
                <div class="right_list">
                    BBBB
                </div>
            </li>
            <li>
                <span>3333</span>
                <div class="right_list">
                    CCCCC
                </div>
            </li>
            <li>
                <span>4444</span>
                <div class="right_list">
                    
                </div>
            </li>
            <li>
                <span>5555</span>
                <div class="right_list">
                    
                </div>
            </li>
        </ul>
    </div>
</body>
</html>